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  • 1
    Electronic Resource
    Electronic Resource
    Construction of curvilinear co-ordinate systems and applications to mesh generation (1973)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 7 (1973), S. 461-477 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Computer-oriented mesh generators, which serve as pre-processors to finite element programs, have recently been developed by several investigators to alleviate the frustration and to reduce the amount of time involved in the tedious manual subdividing of a complex structure into finite elements. Our purpose here is to describe how the techniques of bivariate ‘blending-function’ interpolation, which were originally developed for, and applied to, geometric problems of computer-aided design and numerically controlled machining of free-form surfaces such as automobile exterior panels, can be adapted and applied to the problems of mesh generation for finite element analyses. We concentrate attention on the problem of curvilinearly co-ordinating simply connected planar domains R by constructing invertible maps of the unit square S ≡[0, 1] × [0, 1] onto R. Extensions of the methods described herein to shells in 3-space is straightforward and is illustrated by a practical example taken from the automobile industry. Analogous mesh generators for three-dimensional solids can be developed on the basis of the trivariate ‘blending-function’ formulae found at the end of the second section.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620070405
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  • 2
    Electronic Resource
    Electronic Resource
    Punch stretching of sheet metal and differential equations on manifolds (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 269-282 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The goal of mathematical modelling of sheet metal forming processes is to provide predictive tools for use in the design of stamping processes and the selection of sheet materials. Most current approaches to finite element modelling of large deformation, elastic-plastic sheet metal forming problems use a rate form of the virtual work (equilibrium) equations, and a single-field finite element representation of the displacement components. Called the incremental method, this approach does not produce approximations which satisfy the discrete equilibrium equations at all times, and consequently it demands small time steps to insure stability and numerical accuracy. This paper describes a variant of the mixed method in which displacements, stresses, effective strain and pressures are all given separate finite element representations. The equilibrium equations in non-rate form are discretized to produce a system of algebraic equations which are coupled with the constitutive equations and then integrated using state-of-the-art numerical software. When used to model rate sensitive sheet materials in hydrostatic bulging, plane strain punch stretching and hemispherical punch stretching, the new approach proved to be between 6 and 26 times as fast as the old incremental method.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620250120
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  • 3
    Electronic Resource
    Electronic Resource
    Substructured macro elements based on locally blended interpolation (1977)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 11 (1977), S. 1405-1421 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: In this paper we describe a new class of locally refined macro finite elements which are especially amenable to the use of substructuring techniques for the efficient solution of the resulting idealization. The tools and guidelines illustrated by the examples of modelling crack tips, point load singularities and singularities at re-entrant corners should enable an analyst to construct other such blended macro elements specifically tailored to his particular class of problems. The use of such substructured macro elements in finite element calculations permits substantial reduction in the manual effort of data preparation and the computational cost of numerical solution.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620110906
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  • 4
    Electronic Resource
    Electronic Resource
    Blended infinite elements for paraboblic boundary value problems (1978)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 12 (1978), S. 1841-1851 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A common method for numerically approximating two-point parabolic boundary value problems of the form ut = L[u]+f(u) defined of the semi-infinite strip S = [0, 1]×[0, ∞] is to first discretize the spatial operator in the differential equation and then solve for the time evolution. Such an approach typically involves solving a system of algebriaic equations at a sequence of time steps. In this paper we take a different approach and subdivide S into a collection of semi-infinite substrips Si = [xi, xi+1]×[0, ∞], and use blending function techniques to derive finite parameter functions ei(x, t) defined on Si. Spectral matching methods are used in deriving ei to ensure that (u - ei) can be made small on Si. Galerkin's method, with associated integration sover the entire space-time domain S, is then used to generate approximations to u(x, t) based upon the so defined infinite element (ei, Si). Approximations are hence found for all (x, t) in S by solving one well structed system of algebraic equations. We apply the method to several linear and non-linear problms.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620121206
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  • 5
    Electronic Resource
    Electronic Resource
    A new class of transitional blended finite elements for the analysis of solid structuresPresented at the SIAM 30th Anniversary Meeting, Stanford University, 19-23 July 1982. (1984)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 20 (1984), S. 241-253 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Recently developed computer aided design systems for the design and modification of complex physical solids using interactive computer graphics offer the exciting possibility of an integrated design/analysis system. Called geometric modellers, these systems build complex solids from primitive solids (cubes, cylinders, spheres, etc.) and macro solids (combinations of primitives). To provide an effective finite element analysis capability for these systems, methods must be devised to ease the burden of discretizing the solid geometry into a user controlled finite element mesh. In this paper we describe a new class of transitional blended finite elements which make substantially simpler the task of finite element mesh generation and local mesh refinement. Computational experience indicates that numerical accuracy is not compromised by use of these flexible elements.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620200205
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  • 6
    Electronic Resource
    Electronic Resource
    DEM: A new computational approach to sheet metal forming problems (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 847-862 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Many current approaches to finite element modelling of large deformation elastic - plastic forming problems use a rate form of the virtual work (equilibrium) equations, and a finite element representation of the displacement components. Called the incremental method, this approach produces a three-field formulation in which displacements, stresses and effective strain are dependent variables. Next, the formulation is converted to a one-field displacement formulation by an algebraic time discretization which uses a low order explicit time-stepping procedure to integrate the equations. This approach does not produce approximations which satisfy the discrete equilibrium equations at all times and, moreover, the advantage of the single-field algebraic formulation is realized at the expense of very small time steps needed to produce stability and accuracy in the numerical calculations.This paper describes a variant of the mixed method in which all three field variables (displacements, stresses and effective strain) are given finite element representations. The discrete equilibrium equations then generate a nonlinear system of algebraic equations whose solutions represent a manifold, while the constitutive equations form a system of ordinary differential equations. A commercially available, variable time step/variable order code is then used to integrate this differential/algebraic system. When applied to the problem of hydrostatic bulging of a membrane, the new approach requires far less computer time than the incremental method.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620230507
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  • 7
    Electronic Resource
    Electronic Resource
    Geometrically similar elements (1978)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 12 (1978), S. 881-884 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Finite element analyses sometimes involve elements that are simple rescalings of each other. A useful relation is derived between the stiffness matrices of elements which differ by the same scaling factor in all co-ordinate axes and an application is illustrated.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620120512
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  • 8
    Electronic Resource
    Electronic Resource
    The construction of an optimal weakly divergence-free macroelement (1993)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 36 (1993), S. 2245-2262 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The divergence-free finite element method (DFFEM) is a method to find an approximate solution of the Navier-Stokes equations in a divergence-free space. That is, the continuity equation is satisfied a priori. DFFEM eliminates the pressure from the calculations and reduces significantly the dimension of the system to be solved at each time step. For the standard 8-node velocity and 4-node pressure DFFEM, an optimal basis for the weakly divergence-free subspace is constructed such that each basis function has non-zero support on at most nine contiguous elements. Given this basis, weakly divergence-free macroelements are constructed.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620361307
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  • 9
    Electronic Resource
    Electronic Resource
    The metabolism of cobalamin bound to transcobalamin II and to glycoproteins that bind Cbl in HepG2 cells (human hepatoma) (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 124 (1985), S. 507-515 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The binding, internalization, processing and release of labeled cyanocobalamin (CN[57Co]Cbl) bound to human transcobalamin II (TC II) were studied in HepG2 cells, a line of hepatocytes derived from a human hepatoma. The cells bound the TC II-Cbl by specific, high affinity receptors. Within the cell, the CN-Cbl was promptly freed from TC II and the CN-Cbl converted to more active forms including adenosyl Cbl (AdoCbl) and methyl Cbl (MeCbl). Whereas free labeled Cbl was still present at 72 hours after entry, the cells also bound Cbl to an intracellular binder (ICB) presumed to represent the holo enzymes dependent on Cbl. At levels of TC II that saturated the receptors for TC II-Cbl, much of the Cbl entering the cells remained free and was converted to AdoCbl. Under these circumstances the cells released free Cbl, mostly AdoCbl.Human R type binders of Cbl, which are glycoproteins and some having a terminal galactose, were bound by the HepG2 cells. The binding was characteristic of the receptor system responsive to a terminal galactose, or asialoglycoproteins, but was inconsistent and of low affinity. Cbl bound to R binder was internalized and converted to coenzyme forms of Cbl, but the process was much less effective than when the Cbl entered via the TC II receptor system. It was concluded that the receptors for R-Cbl were unlikely to contribute to the physiologic transport of Cbl in man, but may function in some yet unknown way.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041240322
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  • 10
    Electronic Resource
    Electronic Resource
    Cyclic activity of the receptors of cobalamin bound to transcobalamin II (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 133 (1987), S. 187-191 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The activity of receptors specific for human transcobalamin II-Cobalamin (TC II-Cbl) were measured in virus-transformed lymphoblasts, hepatocytes (hepatoma) and diploid fibrolasts. In all three types of human cells the receptor activity increased as cells went from a resting phase to the most actively dividing phase. Receptor activity declined as cell division slowed. The changes in activity of lymphoblasts and hepatocytes were produced by changes in receptor numbe and not by changes in affinity between receptors and TC II-Cbl. The basis of the change in fibroblasts was not clear. The Cbl-dependent methionine synthetase activity of fibroblasts, in contrast, tended to be greatest when the cultures were confluent and replication had slowed. As the fibroblasts became senescent the receptor activity for TC II-Cbl declined and the fluctuations with the phase of the cell were blunted. However, the release of apo TC II from the cells was maintained. These observations must be taken into consideration when the respective cells are used as models. Even more important are the implications of the observations of the changes in receptor activity for TC II-Cbl for the regulation of the entry of Cbl into cells.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041330125
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